The body of the seven-year-old nephew of the singer and film actor Jennifer Hudson was found in Chicago yesterday, five miles from the apartment where his grandmother and uncle were murdered on Friday.

Hudson identified the body of her nephew yesterday afternoon, two days after she had identified the bodies of her mother and brother.

Julian King's body was found covered in plastic between the seats of a vehicle belonging to Jason Hudson, the actor's 29-year-old brother.

Police declined to say how the boy had died, although early reports said he had suffered a single gunshot wound to the back of the head.

Police said last Friday's killings took place when a gunman shot through the door of the apartment in Chicago's Englewood district, killing Hudson's mother, Darnell Donerson, 57. The gunman then entered the apartment and shot her brother.

On Sunday, the former boyfriend of the boy's mother Julia Hudson, was transferred into state custody after he stopped cooperating with police.

William Balfour had been held and questioned as a "person of interest" in the case. After he stopped talking to police he was deemed to have violated the terms of his parole from a 1999 conviction for attempted murder and was transferred to prison.

Yesterday's developments came after the actor had offered a $100,000 reward for the safe return of her nephew.

Hudson came to fame as a finalist in the TV talent show American Idol in 2004. She did not win, but was later offered a lead role in the movie Dreamgirls, alongside Jamie Foxx and Beyoncé Knowles.

After the film's release in 2006, she won the Oscar and the Golden Globe for best supporting actress. She appeared in this year's Sex and the City film and is currently promoting her latest film, The Secret Life of Bees.

Balfour, who has not so far been named as a suspect, served seven years in jail after being convicted of attempted murder and car theft in 1999. He was arrested on Friday night at his girlfriend's apartment. He said he was with her all day, but police sources said she contradicted his account.